Shoichi Hasegawa

Real‐time Rigid Body Simulation for Haptic Interactions Based on Contact Volume of Polygonal Objects

This paper proposes a new method for real‐time rigid body simulations for haptic interactions based on a penalty method regarding contact volume. Analytical methods for calculation of contact forces require too much time to maintain fast update rates for haptic controls. In addition, they prohibit direct connection of haptic interfaces.

Tension based 7-DOF force feedback device: SPIDAR-G

We demonstrate a new intuitive force feedback device for advanced VR applications. Force feedback for the device is tension based and is characterized by 7 degrees of freedom (DOF); 3 DOF for translation, 3 DOF for rotation, and 1 DOF for grasp. The SPIDAR-G (Space Interface Device for Artificial Reality with Grip) will allow users to interact with virtual objects naturally by manipulating two hemispherical grips located in the center of the device frame. We show how to connect the strings between each vertex of grip and each extremity of the frame in order to achieve force feedback. In addition, methodologies will be discussed for calculating translation, orientation and grasp using the length of 8 strings connected to the motors and encoders on the frame. The SPIDAR-G exhibits smooth force feedback, minimized inertia, no backlash, scalability and safety. Such features are attributed to strategic string arrangement and control that results in stable haptic rendering. The design and control of the SPIDAR-G is described in detail and the space graphic user interface system based on the proposed SPIDAR-G system is demonstrated. Experimental results validate the feasibility of the proposed device and reveal its application to virtual reality.

Real-time rigid body simulation based on volumetric penalty method

This paper proposes a new method for real-time rigid body simulations based on a volumetric penalty method. The penalty method, which employs a spring-damper model, is a simple and useful method for real-time simulation of multi-bodies. However the simple penalty method cannot handle face-face contact, because the simple penalty method cannot find the application point of the reflection force. We propose a distributed small spring-damper model to solve the problem. We analyze the intersecting part of bodies and integrate forces and torques from distributed spring-damper models. We implement the simulator and compare our simulator with the simple penalty method. It shows that our simulator solves the face-face contact problem. In addition, we attach a haptic interface to the simulator for interaction. It shows that we are able to interact with a virtual world by haptic interfaces.

A new step-in-place locomotion interface for virtual environment with large display system

The project presents a new locomotion interface for virtual environment with large display system. Users will be able to direct and control the traveling in the VE by in-place stepping and turning actions. Using a turntable technology, Visual feedback is continuously provided though the use of screen of limited size.

Wearable haptic device to present contact sensation based on cutaneous sensation using thin wire

In this paper, we propose a fingertip-mounted type haptic device to present haptic feedback for mixed reality environments with mobile devices. Our research goal is the realization of a device that causes no discomfort to the users and is virtually felt even during equipment. To achieve this, we realized a fingertip-mounted type device to present contact sensation to cutaneous sensation using thin wire to fulfill three required technical specifications; the weight must be lightweight (1.4g), has to have a fast response, and should have few obstacles on the fingertip abdomen. Our device can present virtual objects to users. Moreover, since a response of an actuator also improves, quality force sense presentation is achieved. And the device can overlay the sense of force without barring ordinary manipulation of real objects or other users. We believe that our work enables new entertainment expansion such as users will be able to touch CG character directly using their fingers.

4 + 4 fingers manipulating virtual objects in mixed-reality environment

This paper describes the construction of a prototype system that allows the user to manipulate virtual objects in a mixed-reality environment. The user can perceive haptic sensations at his or her fingertips and see a virtual world with a live image of his or her hands manipulating the virtual objects. The difficulty of constructing such a visual presentation is the problem of merging the real image with correct geometrical occlusion with images of virtual objects in the simulated virtual world. In this paper, a method of solving registration of real and virtual images to produce mixedreality scenes is proposed. We have combined this method with our haptic interface device, SPIDAR-8, to construct a system that integrates these realities by using the sense of touch and vision of real images in the virtual world that can be realized during the manipulation of virtual objects. The implemented results are shown and remaining problems are discussed.

Realtime sonification of the center of gravity for skiing

Control of body position is important in skiing. During turn, novice skiers often lean back and lose their control. Leaning back is natural reaction for people. They arc afraid of the slope or speed. We develop a device to provide realtime sonification feedback of the center of gravity of the skier. The device guides the position of skier. A preliminary experiment shows possibility of improvements that the user become to be able to control their position immediately and even to overcome the afraid of slope and speed.

A fluid resistance map method for real-time haptic interaction with fluids

Haptic interfaces enable us to interact with a virtual world using our sense of touch. This paper presents a method for realizing haptic interaction with water. Our method displays forces acting on rigid objects due to water with a high frame rate (500 Hz). To achieve this, we present a fast method for simulating the dynamics of water. We decompose the dynamics into two parts. One is a linear flow expressed by a wave equation used to compute water waves. The other is a more complex and non-linear flow around the object. The fluid forces due to the non-linear flow is precomputed by solving Navier-Stokes equations, and stored in a database, named the Fluid Resistance Map. The precomputed non-linear flow and the linear flow are combined to compute the forces due to water.

Kobito: virtual brownies

One common way to create imaginary, virtual creatures is to overlay computer graphics images on real scenes. But this method is not sufficient, because it allows people to only see the imaginary creatures. In Kobito: Virtual Brownies, imaginary creatures interact with the real world. They move real objects, and people interact with them through the real objects. The real objects function as a kind of ”haptic interface.” This technology can be used in the fields of design, amusement, and healthcare because it conveys haptic information in addition to the visual information that is delivered in current artificial life systems.

Human scale haptic interaction with a reactive virtual human in a realtime physics simulator

In this paper, we propose a framework for haptic interaction with a reactive virtual human in a physically simulated virtual world. The user controls an avatar in the virtual world via human scale haptic interface and interacts with the virtual human through the avatar. The virtual human recognizes the users motion and reacts to it. We create a virtual boxing system as an application of the proposed framework. We performed an experiment to evaluate the validity of the reaction of the virtual human. We get confirmation that proposed framework creates realistic reactions and users can easily estimate the input motions of the avatar.